An attempt by the All Blacks centre Sonny Bill Williams and the lock Ali Williams to lighten the mood four days out from New Zealand's Rugby World Cup final against France failed.

The pair arrived at a news conference on Wednesday with a carefully rehearsed routine but when the act received only glares of disapproval, Williams and Williams reverted to normal, showing they are better at sincerity than at comedy and painting a vivid picture of an All Blacks team on the cusp of history.

The Williamses, who are not related, began the news conference by pretending to interpret for each other, whispering translations of questions, then providing only the briefest of answers. The act continued to audible groans from the audience until the players were reminded that a New Zealand public desperate to end a long World Cup drought would expect a professional approach before such an important match.

Ali Williams already has a well-established reputation as something of a joker, once turning up to an All Blacks training session dressed in a Spider-Man suit. When he answered questions seriously, the veteran lock was engaging, providing clear insights into the mind-set of the All Blacks players ahead of what may be a life-changing match.

"I think if you're too relaxed then you can overlook the little things, the intricacies of the game but if you're not relaxed enough you get too tense and you don't enjoy the moment," Ali Williams said. "I know some of the guys are a bit frustrated [with the joking] but we're just trying to enjoy the week, we want to have fun and … come Sunday night it will take care of itself and the best team will win."